C-arm holding apparatus and X-ray diagnostic apparatus

ABSTRACT

An X-ray diagnostic apparatus includes a floor rotating arm which is installed at one end on a floor surface so as to be rotatable around a first rotation axis, a C-arm which is mounted on the other end of the floor rotating arm so as to be rotatable around a second rotation axis, an X-ray tube which is mounted on one end of the C-arm, an X-ray detector which is mounted on the other end of the C-arm, and a bed which has a table top provided to be movable along a longitudinal axis. The bed is placed such that the longitudinal axis is spaced apart from the first rotation axis by a predetermined distance.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromprior Japanese Patent Application No. 2005-024572, filed Jan. 31, 2005,the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a C-arm holding apparatus and an X-raydiagnostic apparatus and, more particularly, to a floor type C-armholding apparatus which holds an X-ray generating unit and an X-raydetecting unit so as to make them face each other, and an X-raydiagnostic apparatus having the C-arm holding apparatus.

2. Description of the Related Art

Medical imaging diagnostic techniques using X-ray diagnosticapparatuses, MRI apparatuses, and X-ray CT apparatuses have rapidlyadvanced with improvements in computer technology, and have becomeindispensable to current medical practice.

Recently, X-ray diagnosis has advanced mainly in the field ofcirculatory organs with improvements in catheter techniques. An X-raydiagnostic apparatus for the diagnosis of circulatory organs generallycomprises an X-ray generating unit, an X-ray detecting unit, a holdingapparatus which holds the X-ray generating unit and the X-ray detectingunit, a table top, a signal processing unit, a display unit, and thelike. The holding apparatus allows X-ray imaging at an optimal positionor in an optimal direction by pivoting, rotating, or moving a C-arm orCeiling-traveling C or Ceiling-mounted arm around a patient (to bereferred to as a subject hereinafter).

As a detector used for the X-ray detecting unit of an X-ray diagnosticapparatus, an X-ray film or an I.I. (Image Intensifier) has been used.In an X-ray imaging method using this I.I., X-ray projection data (to bereferred to as projection data hereinafter) obtained when X-raysgenerated by the X-ray generating unit are transmitted through a subjectis converted into an optical image by the I.I., and this optical imageis displayed on a monitor after being converted into an electricalsignal by an X-ray TV camera and digitized. Therefore, the X-ray imagingmethod using the I.I. allows real-time imaging which is impossible inthe film system, and can acquire projection data in the form of digitalsignals. This makes it possible to perform various kinds of imageprocessing. As a substitute for the above I.I., a flat panel detectorcomprising a two-dimensional array of detection elements has recentlyattracted attention. Some of such detectors have already been put intopractical use.

FIG. 8 shows a C-arm holding apparatus used for a conventionalcirculatory organ X-ray diagnostic apparatus. An X-ray generating unit101 is mounted on one end (lower end) of a C-arm 103 of a C-arm holdingapparatus 105, and an X-ray detecting unit 102 comprising, for example,a flat panel detector is mounted on the other end (upper end) of theC-arm 103 so as to face the X-ray generating unit 101. A one-dot dashedline 108 in FIG. 8 represents an imaging central axis (isocenter) whichconnects the focal point of an X-ray tube in the X-ray generating unit101 to the center of the flat panel detector of the X-ray detecting unit102.

The C-arm 103 is held on a stand 105, fixed on a floor surface 106,through an arm holder 104. The C-arm 103 is mounted on an end portion ofthe arm holder 104 so as to be slidable in the direction indicated by anarrow a. The arm holder 104 is mounted on the upper portion of the stand105 so as to be pivotal or rotatable in the direction indicated by anarrow b. The stand 105 comprises a stand fixed portion 105 a fixed onthe floor surface 106 and a stand movable portion 105 b which can pivotabout the column axis in the direction indicated by an arrow c.

The X-ray generating unit 101 and X-ray detecting unit 102 (to becollectively referred to as an imaging system hereinafter) are set at anoptimal position in an optimal direction with respect to a subject (notshown) placed on a table top 107 by sliding the C-arm 103 in thedirection a and pivoting the arm holder 104 in the direction b. Inaddition, the imaging system and the C-arm 103 can be retracted from thesubject by pivoting the stand movable portion 105 b in the direction c.Retracting the imaging system and the C-arm 103 makes it possible toensure a working space around the head of the subject for a doctor or anexaminer (to be referred to as an operator hereinafter) and facilitatereplacement or repositioning of the subject on the table top 107 beforeor after examination, placement of anesthesia equipment, and the like.

Note that as the arm holder 104 described above, an L-shaped offset armis generally used as shown in FIG. 8. Making the arm holder 104 have anL shape allows the C-arm 103 to be placed on a side of the table top107. This makes it possible to move an end portion of the table top 107in the longitudinal direction to near the stand 105 in the directionindicated by an arrow d. That is, using the L-shaped arm holder 104makes it possible to enlarge the moving range of the table top 107 andexpand the imaging range with respect to the subject. In addition, the Lshape of the arm holder 104 have an advantage of being able to ensure aworking space around the head of a subject for an operator.

However, the ensurance of a working space or the enlargement of theimaging range by pivoting the stand movable portion 105 b or using theL-shaped arm holder 104 has its own limit because the stand 105 is fixedon the floor surface 106, and hence is not necessarily sufficient forthe operator.

In order to solve such problems, a method has been proposed in which aceiling-mounted C-arm holding apparatus having an arm whose one end ispivotally mounted on the ceiling and an arm holder mounted on the otherend of the arm is used, and an imaging region of a subject can bearbitrarily set by aligning the position of the pivot axis of the armwith the central line of a table top in the longitudinal direction (seeJpn. Pat. Appln. KOKAI Publication No. 2000-70248).

According to the method disclosed in the above reference, since the armholder is held on the ceiling through the arm, this holding apparatushas no stand fixed on the floor surface, unlike the conventional floortype C-arm holding apparatus shown in FIG. 8. Therefore, there is noobstacle to the movement of the table top, and the imaging system can beset at an optimal position with respect to any imaging target region ofa subject.

However, the C-arm holding apparatus of a circulatory organ X-raydiagnostic apparatus is basically a floor type apparatus. It istherefore necessary for this floor type C-arm holding apparatus toensure a sufficient work space and allow easy X-ray imaging at anarbitrary position without any limitation on the imaging range. In adual plane system having an imaging system for cardiac angio, which isused for X-ray imaging with a relatively narrow field of view, and animaging system for general angio, which is used for X-ray imaging with awide field of view, e.g., imaging of the head or the lower limbs, twoC-arm holding apparatuses, i.e., a floor type apparatus and aceiling-traveling type apparatus, must be selectively used. When, inparticular, the ceiling-traveling C-arm holding apparatus is to be used,it is desired that the floor type C-arm holding apparatus be retractedto an optimal area.

BRIEF SUMMARY OF THE INVENTION

It is an object of the present invention to provide a floor type C-armholding apparatus with a high degree of freedom in operation, and anX-ray diagnostic apparatus.

According to an aspect of the present invention, there is provided anX-ray diagnostic apparatus comprising a floor rotating arm which isinstalled at one end on a floor surface so as to be rotatable around afirst rotation axis, a C-arm which is mounted on the other end of thefloor rotating arm so as to be rotatable around a second rotation axis,an X-ray tube which is mounted on one end of the C-arm, an X-raydetector which is mounted on the other end of the C-arm, and a bed whichhas a table top provided to be movable along a longitudinal axis, thebed being placed such that the longitudinal axis is spaced apart fromthe first rotation axis by a predetermined distance.

Additional objects and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and obtained by means ofthe instrumentalities and combinations particularly pointed outhereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the invention, andtogether with the general description given above and the detaileddescription of the embodiments given below, serve to explain theprinciples of the invention.

FIG. 1 is a block diagram showing the overall arrangement of an X-raydiagnostic apparatus according to an embodiment of the presentinvention;

FIG. 2 is a view showing the arrangement of a C-arm holding apparatusaccording to the embodiment;

FIG. 3 is a block diagram showing a method of supplying driving signalsto a sliding mechanism, pivoting mechanism, and moving mechanismprovided for the C-arm holding apparatus and a table top in theembodiment;

FIG. 4A is a view for explaining a “lateral placement mode” in theembodiment;

FIG. 4B is a view for explaining a “head-first placement mode” in theembodiment;

FIG. 5 is a view showing the retraction position of the C-arm holdingapparatus in the embodiment;

FIG. 6 is a perspective view showing a ceiling-traveling C-arm holdingapparatus and a floor type C-arm holding apparatus according to amodification of the embodiment;

FIG. 7A is a view showing the retraction position of the floor typeC-arm holding apparatus according to the modification of the embodiment;

FIG. 7B is a view showing the retraction position of theceiling-traveling C-arm holding apparatus according to the modificationof the embodiment;

FIG. 8 is a perspective view showing a conventional floor type C-armholding apparatus;

FIG. 9A is a perspective view of a C-arm holding apparatus in FIG. 2;and

FIG. 9B is a side view of the C-arm holding apparatus in FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

In the embodiment of the present invention which will be describedbelow, the stand of a C-arm holding apparatus is pivotally mounted onone end of a floor rotating arm having the other end pivotally mountedon the floor surface, and a C-arm having an imaging system (an X-raygenerating unit and an X-ray detecting unit) mounted on its end portionis mounted on the stand through an arm holder. The stand and the C-armand imaging system mounted on the stand are moved to predeterminedpositions in predetermined directions by pivoting the floor rotating armand the stand.

(Arrangement of Apparatus)

The arrangement of an X-ray diagnostic apparatus according to anembodiment of the present invention will be described with reference toFIGS. 1 to 3. FIG. 1 is a block diagram showing the overall arrangementof the X-ray diagnostic apparatus. FIG. 2 is a view showing thearrangement of the C-arm holding apparatus.

An X-ray diagnostic apparatus 100 comprises an X-ray generating unit 1which applies X-rays to a subject 150, an X-ray detecting unit 2 whichtwo-dimensionally detects X-rays transmitted through the subject 150 andgenerates X-ray projection data on the basis of the X-ray detectiondata, a C-arm holding apparatus 5 which holds the X-ray generating unit1 and the X-ray detecting unit 2, a table top 17 on which the subject150 is to be placed, and a high voltage generating unit 4 whichgenerates a high voltage necessary for X-ray application by the X-raygenerating unit 1.

The X-ray diagnostic apparatus 100 comprises a moving mechanism drivingunit 3 which supplies driving signals to a sliding mechanism, pivotingmechanism, and moving mechanism provided for the C-arm holding apparatus5 and the table top 17, an image processing storage unit 7 whichgenerates and stores image data on the basis of the X-ray projectiondata generated by the X-ray detecting unit 2, and a display unit 8 whichdisplays desired image data of a plurality of frames of image datastored in the image processing storage unit 7.

The X-ray diagnostic apparatus 100 further has an operation unit 9 whichis used to, for example, select and set subject information, imagingconditions, display conditions, X-ray application conditions, and thelike and input various commands, and a system control unit 10 whichsystematically controls the above units of the X-ray diagnosticapparatus 100.

The X-ray generating unit 1 comprises an X-ray tube 15 which appliesX-rays to the subject 150 and an X-ray stable top 16 which forms X-raysapplied from the X-ray tube 15 into an X-ray cone (cone beam). The X-raytube 15 is a vacuum tube which generates X-rays and generates X-rays byaccelerating electrons emitted from a cathode (filament) using a highvoltage and making the electrons collide with a tungsten anode. TheX-ray stable top 16 is placed between the X-ray tube 15 and the subject150 and has a function of reducing the size of an X-ray beam appliedfrom the X-ray tube 15 into a predetermined irradiation size.

The X-ray detecting unit 2 comprises a flat panel detector 21 whichconverts X-rays transmitted through the subject 150 into charge andstores it, a gate driver 22 which reads out charge stored in the flatpanel detector 21, and a projection data generating unit 13 whichgenerates X-ray projection data from the read charge.

The flat panel detector 21 is formed by two-dimensionally arrayingminute detection elements in the column and line directions. Eachdetection element comprises a photoelectric film which detects X-raysand generates charge in accordance with the amount of incident X-rays, acharge storage capacitor which stores charge generated in thephotoelectric film, and a Thin-Film Transistor (TFT) which reads outcharge stored in the charge storage capacitor at a predetermined timing.

The projection data generating unit 13 comprises a charge/voltageconverter 23 which converts the charge read by the flat panel detector21 into a voltage, an A/D converter 24 which converts an output from thecharge/voltage converter 23 into a digital signal, and a parallel/serialconverter 25 which converts X-ray projection data, which is parallellyread from the flat panel detector 21 on a line basis and digitallyconverted, into a time-series signal.

The moving mechanism driving unit 3 comprises a C-arm holding apparatusmechanism driving unit 31 which supplies driving signals to a slidingmechanism, pivoting mechanism, and moving mechanism provided for theC-arm holding apparatus 5 (to be described later), a table top mechanismdriving unit 32 which supplies driving signals for the movement of thetable top 17 in the vertical direction and along a longitudinal axis LA,and a moving mechanism driving unit control unit 33 which controls theC-arm holding apparatus mechanism driving unit 31 and the table topmechanism driving unit 32.

The arrangement of the C-arm holding apparatus 5 which is the mostimportant portion of this embodiment will be described next withreference to FIG. 2. FIG. 2 shows the C-arm holding apparatus 5 on whichthe X-ray generating unit 1 and the X-ray detecting unit 2 are mountedand the table top 17 on which the subject 150 is placed. Referring toFIG. 2, for the sake of descriptive convenience, the body axis directionof the subject 150, i.e., the longitudinal axis LA of the table top 17,is set as the Y-axis, the central axis direction (pivot axis direction)of a stand 53 is set as the Z-axis, and the direction perpendicular tothe Y-axis and the Z-axis is set as the X-axis. However, the body axisdirection of the subject 150 can be set to an arbitrary direction withrespect to the C-arm holding apparatus 5.

Like the conventional C-arm holding apparatus 110 shown in FIG. 8, theC-arm holding apparatus 5 is designed such that the X-ray generatingunit 1 is mounted on one end (lower end) of a C-arm 51, and the X-raydetecting unit 2 is mounted on the other end (upper end) of the C-arm 51so as to face the X-ray generating unit 1.

The C-arm 51 is held on the stand 53 through an arm holder 52. The C-arm51 is mounted on a side surface of the arm holder 52 so as to beslidable in the direction indicated by an arrow a. The arm holder 52 ismounted on the stand 53 so as to be pivotal about a pivot axis in thedirection indicated by an arrow b, i.e., the X direction. As the armholder 52 pivots, the C-arm 51 pivots about the pivot axis in the Xdirection. By sliding the C-arm 51 in the direction a and pivoting thearm holder 52 in the direction b, the imaging system mounted on the twoend portions of the C-arm 51 is set at an arbitrary position withrespect to the subject 150 placed on the table top 17.

A floor rotating arm 54 is placed on a floor surface 59. One end of thefloor rotating arm 54 is mounted on the floor surface 59 so as to bepivotal about a rotation axis Z1 (first pivot axis), and the stand 53 ismounted on the other end of the floor rotating arm 54 so as to bepivotal about a rotation axis Z2 (second pivot axis). In this case, boththe rotation axis Z1 of the floor rotating arm 54 and the rotation axisZ2 of the stand 53 are set to be located in the Z direction. Pivotingthe floor rotating arm 54 about the rotation axis Z1 makes it possibleto retract the stand 53, arm holder 52, and C-arm 51 to positionsdistant from the subject 150.

In addition, combining the pivotal movement of the floor rotating arm 54and the pivotal movement of the stand 53 about the rotation axis Z2 onthe floor rotating arm 54 makes it possible to set the imaging system atan arbitrary position in an arbitrary direction with respect to thesubject 150 without interference from the stand 53. This allows X-rayimaging in a wide range from the head to the lower limbs and facilitates“head-first placement” and “lateral placement” of the imaging systemwith respect to the subject 150. The effects of this embodiment withrespect to “head-first placement” and “lateral placement” of the imagingsystem will be described in detail later.

A C-arm sliding mechanism 511 for sliding the C-arm 51 is provided atthe joint portion between the arm holder 52 and the C-arm 51. An armholder pivoting mechanism 512 for pivoting the arm holder 52 is providedat the joint portion between the stand 53 and the arm holder 52. Inaddition, a stand pivoting mechanism 513 for pivoting the stand 53 isprovided at the joint portion between the floor rotating arm 54 and thestand 53. A floor rotating arm pivoting mechanism 514 for pivoting thefloor rotating arm 54 is provided at the joint portion between the floorrotating arm 54 and the floor surface 59. These mechanisms are not shownin FIG. 2.

The C-arm holding apparatus 5 will be described in detail.

As shown in FIGS. 9A and 9B, the floor rotating arm 54 is provided, atone end, on the floor surface so as to be rotatable (d) around thesubstantially vertical first rotation axis Z1. The stand 53 is supportedon the other end of the floor rotating arm 54 so as to be rotatable (c)around the substantially vertical second rotation axis Z2. The armholder 52 is supported on the stand 53 so as to be rotatable (B) arounda substantially horizontal third rotation axis (C-arm horizontalrotation axis) Z3. The C-arm 51 is supported on the arm holder 52 so asto be slidable/rotatable around a substantially horizontal fourthrotation axis (slide rotation axis) Z4 perpendicular to the C-armhorizontal rotation axis Z3. The X-ray generating unit 1 is-mounted onone end of the C-arm 51. The X-ray detecting unit 2 is mounted on theother end of the C-arm 51.

This apparatus is designed such that the X-ray focal point of the X-raygenerating unit 1 and the imaging axis passing through the center of thedetection surface of the X-ray detecting unit 2 cross the C-armhorizontal rotation axis Z3 and the slide rotation axis Z4 at one point.As is known, the absolute coordinates of the intersection (a position onthe imaging room coordinate system) does not displace even when theC-arm 51 rotates around the C-arm horizontal rotation axis Z3 androtates around the slide rotation axis Z4 as long as the floor rotatingarm 54 does not rotate around the first rotation axis Z1, and the stand53 does not rotate around the second rotation axis Z2, and is generallycalled an isocenter.

As shown in FIGS. 9A, 9B, and 5, this apparatus is designed such thatwhen the rotational angle of the stand 53 around the second rotationaxis Z2 is set at a reference angle (0°) and the C-arm 51 overlaps thefloor rotating arm 54 and is folded into the minimum posture, theisocenter is located at the first rotation axis Z1 of the floor rotatingarm 54, that is, the imaging axis, the C-arm horizontal rotation axisZ3, and slide rotation axis Z4 cross the first rotation axis Z1 of thefloor rotating arm 54 at the isocenter. That is, the length of the floorrotating arm 54, the size of the stand 53, the size of the arm holder52, and the radius of the C-arm 51 are comprehensively determined suchthat the distance between the first rotation axis Z1 of the floorrotating arm 54 and the second rotation axis Z2 of the stand 53 becomesequal to the distance between the second rotation axis Z2 of the stand53 and the isocenter.

Assume that the rotational angle of the C-arm 51 around the C-armhorizontal rotation axis Z3 is at the reference angle (0°), and therotational angle of the C-arm 51 around the slide rotation axis Z4 is atthe reference angle (0°) to set the imaging axis in the verticaldirection. According to the above designs, in this case, when therotational angle of the stand 53 around the second rotation axis Z2 isat the reference angle (0°), the imaging axis substantially coincideswith the first rotation axis Z1 of the floor rotating arm 54.

Such structural characteristics act advantageously in various respectsin imaging operation.

As shown in FIG. 3, each mechanism described above slides or pivots to adesired position by a driving signal supplied from the C-arm holdingapparatus mechanism driving unit 31 of the moving mechanism driving unit3 on the basis of a control signal from the system control unit 10.

Referring to FIG. 2, the table top 17 on which the subject 150 is placedis provided with a table top longitudinal direction moving mechanism 171(not shown) for moving the table top 17 in the body axis direction ofthe subject 150, i.e., the Y direction of the table top longitudinalaxis LA, and a table top vertical direction moving mechanism 172 (notshown) for moving the table top 17 in the vertical direction (Zdirection). Each of these moving mechanisms is moved to a desiredposition by a driving signal supplied from the table top mechanismdriving unit 32 of the moving mechanism driving unit 3 on the basis of acontrol signal from the system control unit 10.

Referring back to FIG. 1, the high voltage generating unit 4 comprises ahigh voltage generator 42 which generates a high voltage to be appliedbetween the anode and the cathode to accelerate thermal electronsgenerated from the cathode of the X-ray tube 15, and an X-ray controlunit 41 which controls X-ray application conditions such as a tubecurrent, tube voltage, and application time in the high voltagegenerator 42 in accordance with an instruction signal from the systemcontrol unit 10.

An image data storage circuit 72 of the image processing storage unit 7generates image data by sequentially storing X-ray projection dataoutput from the projection data generating unit 13 of the X-raydetecting unit 2 on a line basis. An image processing circuit 71 has animage processing function of, for example, generating DSA image data byperforming differential processing with respect to image data generatedby the image data storage circuit 72 on the basis of mask image data andcontrast image data which are obtained in X-ray imaging before and afterinjection of a contrast medium.

The operation unit 9 is an interactive interface comprising inputdevices such as a keyboard, trackball, joy stick, and mouse, a displaypanel, various kinds of switches, and the like, and is used to, forexample, input subject information, set X-ray application conditions andan image magnification, select the “imaging system placement mode” or“retraction mode”, set an imaging system position and direction, andinput various kinds of commands such as an imaging start command. Notethat the X-ray application conditions include a tube voltage to beapplied to the X-ray tube 15, a tube current, X-ray application time,and the like, and the subject information includes an age, sex,physique, examination region, examination method, diagnosis history, andthe like. In addition, the “imaging system placement mode” includes a“head-first placement mode” and a “lateral placement mode”.

The display unit 8 displays the image data generated by the image datastorage circuit 72 of the image processing storage unit 7. The systemcontrol unit 10 comprises a CPU and storage circuit (not shown)temporarily stores pieces of information such as command signals andvarious kinds of initial setting conditions input by the operator, whichare supplied from the operation unit 9, and then systematically controlsthe respective units of the X-ray diagnostic apparatus 100 on the basisof these pieces of information.

An example of installation of the C-arm holding apparatus 5 in thisembodiment will be described next with reference to FIGS. 4A, 4B, and 5.FIG. 4A shows a so-called “lateral placement mode” in which the imagingsystem is placed from a side of the subject by using the C-arm holdingapparatus 5. When a user instruction associated with the activation ofthe “lateral placement mode” is input through the operation unit 9, themoving mechanism driving unit control unit 33 realizes the placementshown in FIG. 4A by controlling the respective units in response to theuser instruction. That is, the floor rotating arm 54 pivots about therotation axis Z1 so as to be positioned substantially parallel to thelongitudinal axis LA of the table top 17, and the stand 53 pivots aboutthe rotation axis Z2 of the floor rotating arm 54 so as to make theC-arm 51 cross the longitudinal axis LA at a substantially right angle.

In performing X-ray imaging while moving the table top 17 in thelongitudinal direction, placing the stand 53 on a side of the table top17 makes it possible to perform X-ray imaging in a wide range from thehead to the lower limbs because the moving range of the table top 17 isnot restricted by the stand 53. Note, however, that a distance Lg is setbetween the rotation axis Z1 of the floor rotating arm 54 mounted on thefloor surface 59 and the central axis of the table top 17 so as not tocause the table top 17 to come into contact with the stand 53 even if itmoves in the longitudinal direction.

FIG. 4B shows a so-called “head-first placement mode” in which theimaging system is placed from the body axis direction of the head byusing the C-arm holding apparatus 5. When a user instruction associatedwith the activation of the “head-first placement mode” is input throughthe operation unit 9, the moving mechanism driving unit control unit 33realizes the placement shown in FIG. 4B by controlling the respectiveunits in response to the user instruction. That is, the floor rotatingarm 54 pivots about the rotation axis Z1 so as to be positionedsubstantially vertical to the longitudinal direction (Y direction) ofthe table top 17. The stand 53 placed on the other end of the floorrotating arm 54 then pivots about the rotation axis Z2 so as to make theC-arm 51 become substantially parallel to the longitudinal direction ofthe table top 17. In this case, the stand 53 is placed on thesubstantially central axis of the table top 17. By pivoting the floorrotating arm 54 about the rotation axis Z1, the stand 53 is placed onthe substantially central axis of the table top 17. This makes itpossible to perform the conventional “head-first placement mode”.

FIG. 5 shows the retraction position of the C-arm holding apparatus 5 atthe time of interruption or stable toppage of X-ray imaging. When a userinstruction associated with the activation of the “retraction mode” isinput through the operation unit 9, the moving mechanism driving unitcontrol unit 33 realizes the placement shown in FIG. 5 by controllingthe respective units in response to the user instruction. That is, thefloor rotating arm 54 pivots about the rotation axis Z1 so as to bepositioned substantially parallel to the longitudinal axis (Y direction)of the table top 17, and the stand 53 pivots about the rotation axis Z2of the floor rotating arm 54 so as to make the C-arm 51 become parallelto the longitudinal direction of the table top 17. In this case, theabove floor rotating arm 54 and stand 53 are pivoted such that theimaging central axis (isocenter) of the imaging system mounted on theC-arm 51 substantially coincides with the rotation axis Z1 of the floorrotating arm 54, and the C-arm 51 overlaps on the floor rotating arm 54.

The pivoting mechanisms in the C-arm holding apparatus 5 in thisembodiment are realized by motor-driven operation. When the operatorselects the “head-first placement mode” or “lateral placement mode” inselecting an “imaging system placement mode” using the operation unit 9,this selection information is supplied to the moving mechanism drivingunit control unit 33 of the moving mechanism driving unit 3 through thesystem control unit 10. Upon receiving the selection information, themoving mechanism driving unit control unit 33 supplies a driving controlsignal to the C-arm holding apparatus mechanism driving unit 31. TheC-arm holding apparatus mechanism driving unit 31 supplies, to the floorrotating arm pivoting mechanism 514 and stand pivoting mechanism 513provided on the C-arm holding apparatus 5, a driving signal for pivotingthe floor rotating arm 54 about the rotation axis Z1 and a drivingsignal for pivoting the stand 53 about the rotation axis Z2. Bysupplying these driving signals to the floor rotating arm pivotingmechanism 514 and the stand pivoting mechanism 513, “lateral placement”or “head-first placement” of the imaging system shown in FIG. 4A or 4Bis performed.

In the same manner, when the “retraction mode” for retracting the C-armholding apparatus 5 is selected by the operator using the operation unit9 at the time of interruption or stable toppage of X-ray imaging, theC-arm holding apparatus mechanism driving unit 31 of the movingmechanism driving unit 3 supplies, on the basis of a selection signalfrom the operation unit 9, driving signals to the floor rotating armpivoting mechanism 514 and the stand pivoting mechanism 513 by the samesequence as that for the “head-first placement mode” or “lateralplacement mode” described above. The C-arm holding apparatus 5 shown inFIG. 5 is then retracted on the basis of these driving signals.

According to this embodiment described above, pivotally mounting thestand of the C-arm holding apparatus on one end of the floor rotatingarm having the other end pivotally mounted on the floor surface makes itpossible to place the stand outside the moving range of the table top.For this reason, even if the table top is moved in the longitudinaldirection, it does not come into contact with the C-arm holdingapparatus. This makes it possible to perform X-ray imaging with respectto the subject at an arbitrary position in an arbitrary directionwithout much restriction on the imaging range. In the “lateral placementmode”, in particular, since no restriction is imposed on the movingrange of the table top, X-ray imaging can be performed in a wide rangefrom the head to the lower limbs.

In addition, since there is no need to install the stand of the C-armholding apparatus around the subject placed on the table top, asufficient working space can be ensured, and replacement orrepositioning of the subject on the table top before or afterexamination, placement of anesthesia equipment, and the like arefacilitated.

(Modification)

A modification of this embodiment will be described next with referenceto FIGS. 6 to 8. The X-ray diagnostic apparatus according to thismodification comprises a floor type C-arm holding apparatus like that inthe above embodiment and a ceiling-traveling C-arm holding apparatus.That is, as shown in FIG. 6, this apparatus comprises a first imagingsystem having an X-ray generating unit 1 a and an X-ray detecting unit 2a arranged on both sides of the subject (not shown) placed on the tabletop 17, and a second imaging system having an X-ray generating unit 1 band an X-ray detecting unit 2 b. The X-ray generating unit 1 a and theX-ray detecting unit 2 a are mounted on a ceiling-traveling C-armholding apparatus 5 a, and the X-ray generating unit 1 b and the X-raydetecting unit 2 b are mounted on a floor type C-arm holding apparatus 5b having an arrangement similar to that in the above embodiment. In thiscase, the moving mechanism driving unit 3, image processing storage unit7, display unit 8, operation unit 9, and system control unit 10 areshared between the above two C-arm holding apparatuses. The functions ofthese units are almost the same as those shown in FIG. 11, and hence adetailed description thereof will be omitted.

For the sake of descriptive convenience, FIG. 6 shows the case whereinthe two imaging systems are arranged around the table top 17. Inpractice, however, the operator selects a desired imaging system and theC-arm holding apparatus on which the imaging system is mounted by usingthe operation unit 9, and the C-arm holding apparatus which is notselected is automatically retracted to a predetermined area.

That is, the X-ray diagnostic apparatus of this modification is a dualplane system having an imaging system for cardiac angio, which is usedfor X-ray imaging with a relatively narrow field of view, and an imagingsystem for general angio, which is used for X-ray imaging with a widefield of view, e.g., imaging of the head or the lower limbs. The imagingsystem for cardiac angio is mounted on the floor type C-arm holdingapparatus 5 b. The imaging system for general angio is mounted on theceiling-traveling C-arm holding apparatus 5 a. When X-ray imaging in the“head-first placement mode” is to be performed by using theceiling-traveling C-arm holding apparatus 5 a in this dual plane system,since the stand of the conventional floor type C-arm holding apparatusis fixed within the moving range of the table top, the stand comes intocontact with the ceiling-traveling C-arm holding apparatus, resulting indifficulty in performing X-ray imaging in the “head-first placementmode”.

FIG. 7A shows the positional relationship between the ceiling-travelingC-arm holding apparatus 5 a and the retracted floor type C-arm holdingapparatus 5 b in this modification. When a user instruction associatedwith the activation of the “floor type C-arm retraction mode” is inputthrough the operation unit 9, the moving mechanism driving unit controlunit 33 realizes the placement shown in FIG. 7A by controlling therespective units in response to the user instruction. Ceiling-travelingrails 112 are arranged on the ceiling of the examination room, and aslider base 111 is placed to be perpendicular to the ceiling-travelingrails. By moving an arm holder 52 a of the ceiling-traveling C-armholding apparatus 5 a along the above ceiling-traveling rails 112 andthe slider base 111, a C-arm 51 a mounted on the arm holder 52 a can bemoved to a desired position. FIGS. 7A and 7B show the “head-firstplacement” of the ceiling-traveling C-arm holding apparatus 5 a. In thiscase, since the floor type C-arm holding apparatus 5 b is retracted to aside of the table top 17 at the distance Lg as in the case shown in FIG.5, “head-first placement” by the ceiling-traveling C-arm holdingapparatus 5 a, which has been difficult to perform, is facilitated.

Note that the above floor type C-arm holding apparatus 5 b is retractedon the basis of the selection information of the C-arm holding apparatusin the operation unit 9. A C-arm 51 b is retracted outside the rotatingrange of the ceiling-traveling C-arm 51 a. That is, the central axis ofthe ceiling-traveling C-arm 51 a almost coincides with the longitudinalaxis, and the C-arm 51 b rotates so as to be almost parallel to thelongitudinal axis. In addition, the C-arm 51 b is retracted outside therotating range of the ceiling-traveling C-arm 51 a.

When the operator selects the ceiling-traveling C-arm holding apparatus5 a in selecting a C-arm holding apparatus by using the operation unit9, the selection information is supplied to the moving mechanism drivingunit control unit 33 of the moving mechanism driving unit 3 through thesystem control unit 10. Upon receiving this selection information, themoving mechanism driving unit control unit 33 supplies a driving controlsignal to the C-arm holding apparatus mechanism driving unit 31. TheC-arm holding apparatus mechanism driving unit 31 supplies drivingsignals for pivoting a floor rotating arm 54 b and a stand 53 b to afloor rotating arm pivoting mechanism 514 b and stand pivoting mechanism513 b (not shown) provided on the floor type C-arm holding apparatus 5b. By supplying these driving signals to the floor rotating arm pivotingmechanism 514 b and the stand pivoting mechanism 513 b, the floor typeC-arm holding apparatus 5 b shown in FIG. 7A is retracted.

FIG. 7B shows the positional relationship between the floor type C-armholding apparatus 5 b and the retracted ceiling-traveling C-arm holdingapparatus 5 a in this modification. When a user instruction associatedwith the activation of the “ceiling-traveling C-arm retraction mode” isinput through the operation unit 9, the moving mechanism driving unitcontrol unit 33 realizes the placement shown in FIG. 7B by controllingthe respective units in response to the user instruction. The controlunit 33 controls rotation of the C-arm 51 b, movement of the slider base111, movement of arm holder 52 a, and rotation of the ceiling-travelingC-arm 51 a in accordance with predetermined user instructions such thatthe central axis of the C-arm 51 b which connects the first rotationaxis Z1 to the second rotation axis Z2 is almost perpendicular to thelongitudinal axis, and the ceiling-traveling C-arm 51 a is retractedoutside the rotating range of the C-arm 51 b.

According to the above modification of this embodiment, when X-rayimaging is to be performed by using the ceiling-traveling C-arm holdingapparatus of the X-ray diagnostic apparatus having the ceiling-travelingC-arm holding apparatus and the floor type C-arm holding apparatus, thestand of the floor type C-arm holding apparatus is pivotally mounted onone end of the floor rotating arm having the other end pivotally mountedon the floor surface. This makes it possible to retract the floor typeC-arm holding apparatus to an area where it does not come into contactwith the ceiling-traveling C-arm holding apparatus. Therefore,“head-first placement” using the ceiling-traveling C-arm holdingapparatus, which has been difficult to perform, can be easily performed,and X-ray imaging can be performed at an optimal position or in anoptimal direction in accordance with a purpose.

The embodiment of the present invention has been described above.However, the present invention is not limited to the above embodiment,and can be modified. For example, in the above embodiment, the rotationaxis Z1 of the floor rotating arm 54 is spaced apart from thelongitudinal central axis of the table top 17 by the predetermineddistance Lg like the rotation axis Z2 of the stand 53. However, thefloor rotating arm 54 moves near the floor surface 59, and hence doesnot interfere with the movement of the table top 17. For this reason,the floor rotating arm 54 can also be installed on the longitudinalcentral axis of the table top 17 within the longitudinal moving range ofthe table top 17.

The above embodiment has exemplified the case wherein the arm holder 52,stand 53, and floor rotating arm 54 each are designed to pivot. However,some or all of them may be designed to rotate.

The pivoting and rotating mechanisms for them are preferably operatedremotely from the operation unit 9. However, adding manual operation bythe operator makes it possible to facilitate fine adjustment of a movingposition and retraction position.

In addition, according to the above description, when the C-arm holdingapparatus 5 is to be retracted in FIG. 5, the imaging axis of theimaging system mounted on the C-arm 51 almost coincides with therotation axis Z1 of the floor rotating arm 54. However, the presentinvention is not limited to this.

Note that the above embodiment has exemplified the X-ray detecting unit2 having the flat panel detector 21. However, an X-ray detecting unithaving an X-ray I.I. or the like may be used.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

1. An X-ray diagnostic apparatus comprising: a floor rotating arminstalled at one end on a floor surface so as to be rotatable around afirst rotation axis; a C-arm mounted on the other end of the floorrotating arm so as to be rotatable around a second rotation axis; anX-ray tube mounted on one end of the C-arm; an X-ray detector mounted onthe other end of the C-arm; and a bed including a table top provided tobe movable along a longitudinal axis, the bed being placed such that thelongitudinal axis is spaced apart from the first rotation axis by apredetermined distance, wherein a distance between the second rotationaxis and an imaging axis is substantially equal to a distance betweenthe first rotation axis and the second rotation axis, and the imagingaxis is an axis which connects an X-ray focal point of the X-ray tube toa center of the X-ray detector, wherein a distance between thelongitudinal axis and the first rotation axis is equal to a distancebetween the first rotation axis and the second rotation axis.
 2. Anapparatus according to claim 1, further comprising a control unit whichcontrols rotation of the floor rotating arm in accordance with apredetermined user instruction such that a central axis of the floorrotating arm which connects the first rotation axis and the secondrotation axis becomes substantially parallel to the longitudinal axis.3. An apparatus according to claim 2, wherein the control unit controlsrotation of the C-arm in accordance with the predetermined userinstruction such that a central axis of the C-arm which connects thesecond rotation axis and the imaging axis becomes substantiallyperpendicular to the longitudinal axis.
 4. An apparatus according toclaim 2, wherein the control unit controls rotation of the C-arm inaccordance with the predetermined user instruction such that the C-armoverlaps on the floor rotating arm.
 5. An apparatus according to claim1, further comprising a control unit which controls rotation of thefloor rotating arm in accordance with a predetermined user instructionsuch that a central axis of the floor rotating arm which connects thefirst rotation axis and the second rotating axis becomes substantiallyperpendicular to the longitudinal axis.
 6. An apparatus according toclaim 5, wherein the control unit controls rotation of the C-arm inaccordance with the predetermined user instruction such that a centralaxis of the C-arm which connects the second rotation axis and theimaging axis becomes substantially parallel to the longitudinal axis. 7.An apparatus according to claim 1, further comprising a pair ofceiling-traveling rails which are installed on a ceiling so as to besubstantially parallel to the longitudinal direction, a slider basewhich is laid over the ceiling-traveling rails so as to freely travel,an arm holder which is provided on the slider base so as to freelytravel, a ceiling-traveling C-arm which is mounted on the arm holder soas to be rotatable around a third rotation axis, another X-ray tubewhich is mounted on one end of the ceiling-traveling C-arm, and anotherX-ray detector which is mounted on the other end of theceiling-traveling C-arm.
 8. An apparatus according to claim 7, furthercomprising a control unit which controls rotation of the floor rotatingarm, rotation of the C-arm, and rotation of the ceiling-traveling C-armin accordance with predetermined user instructions such that a centralaxis of the ceiling-traveling C-arm substantially coincides with thelongitudinal axis, and the C-arm is retracted outside a rotating rangeof the ceiling-traveling C-arm.
 9. An apparatus according to claim 7,further comprising a control unit which controls rotation of the floorrotating arm, movement of the slider base, movement of the arm holder,and rotation of the ceiling-traveling C-arm in accordance withpredetermined user instructions such that a central axis of the floorrotating arm which connects the first rotation axis and the secondrotation axis becomes substantially perpendicular to the longitudinalaxis, and the ceiling-traveling C-arm is retracted outside a rotatingrange of the floor rotating arm.